Slings, tow-ropes and the like

ABSTRACT

A cargo sling, tow-rope or the like comprises two cables embedded in a continuous elastomeric sheath of generally elliptical cross-section, these cables being disposed substantially in the longitudinal plane containing the major axis of the ellipse and in a substantially symmetrical relationship with the longitudinal centerline of the sheath; the cables extend beyond the sheath on at least one end, their projecting extremities being interconnected to form a loop or to engage an attachment such as an extension cable or a coupling member. The cables may be provided with deformations inside the sheath, such as undulations or shoulders, to prevent relative longitudinal slippage. The sheath can be produced by extrusion about the juxtaposed cables.

United States Patent [191 Brindejonc de Treglode SLINGS, TOW-ROPES ANDTHE LIKE [76] Inventor: Pierre Brindejonc de Treglode, 14

rue Dailly, 92 Saint-Cloud, France 221 Filed: 0a. 8, 1970 21 Appl.No.:79,205

[30] Foreign Application Priority Data Oct. 13, 1969 France ..6935549Sept. 16, 1970 France ..7034l93 [52] U.S. Cl ..24/73, 294/74 [51] Int.Cl ..A44b 31/00, B66c 1/12 [58] Field of Search...24/73 ES, 115 K,122.3, 122.6; 294/30.5 TC, 74

[56] References Cited UNITED STATES PATENTS 2,304,306 12/1942 Hobbs..294/74 X 2,569,912 10/1951 Andersen ....;....294/74 2,643,638 6/1953Villmer ..294/74 X 3,079,192 2/1963 Otley ..294/74 3,018,128 l/l962Nelson et al ..294/74 March 6, 1973 3,310,333 3/1967 Hutson ..294/743,317,233 5/1967 Black ..294/74 3,512,223 5/1970 Willinger ..294/74Primary Examiner-Paul R. Gilliam Attorney-Karl F. Ross [5 7] ABSTRACT Acargo sling, tow-rope or the like comprises two cables embedded in acontinuous elastomeric sheath of generally elliptical cross-section,these cables being disposed substantially in the longitudinal planecontaining the major axis of the ellipse and in a substantiallysymmetrical relationship with the longitudinal centerline of the sheath;the cables extend beyond the sheath on at least one end, theirprojecting extremities being interconnected to form a loop or to-engagean attachment such as an extension cable or a coupling member. Thecables may be provided with deformations inside the sheath, such asundulations or shoulders, to prevent relative longitudinal slippage. The

sheath can be produced by extrusion about the juxtaposed cables.

6 Claims, 29 Drawing Figures PATENTEU 6 I975 3.718.945

SHEET 10F 4 Pierre Brindejonc de Treglode INVENTOR Attorney PATENIEDMARelm 3 71 ,945

7 SHEET 2 [1F 4 Pierre Brindojonc d9 Trcglada INVENTOR AttorneyPATHQ'TED 61973 v 3,718,945

SHEET 3 BF 4 [ml/b,

Pierre Brindojonc do Traglode INVENTOR PATENTEDHAR 61m 3,718,945

SHEET 4 0F 4 Pierre Brindojonc do Tragloda INVENTOR Attorney SLINGS,TOW-ROPES AND THE LIKE My present invention relates to cargo slings,towropes and the like, hereinafter referred to for simplicity as slings.

At the present time it is known to use flat slings in the form ofseveral metal cables embedded in rubber. However, such slings have thedrawback that they operate under adverse conditions if their runs extendobliquely in relation to a load being carried, since the effort is thenexerted along one edge of the sling so that the forces may have to becarried by a single cable, with the result that this particular cablefails.

Furthermore, such slings have hitherto been manufactured by passing ametal cable over pulleys or cylinders in order to form a series ofparallel runs, which are then stretched and finally embedded togetherwith the pulleys or cylinders in a rubber sheath which is subsequentlyvulcanized. This method is expensive, and is restricted to theproduction of slings of predetermined lengths, because a special mold isrequired for each length. The individual cables are spaced apart in thesheath so that the width of the sling becomes substantial for slingshaving a load rating above a given force, and the amount of rubber ismuch larger than that actually required to bind the cables together.

One object of the present invention is to provide an improved slingconstruction which overcomes these drawbacks. i

The sling according to my invention comprises two cables embedded in anelastomeric'sheath of generally elliptical cross-section, the cablesbeing located substantially in the longitudinal plane containing themajor axis of the ellipse and in a substantially symmetrical manner oneither side of the longitudinal centerline of the sheath; the cablesproject from the sheath on at least one end, where they are connectedtogether to form a loop or to engage an attachment.

Thanks to this arrangement, the sling can be disposed skew to the loadbeing lifted without any ill effect, the resulting stresses beingreadily transmitted from one cable to the other. Furthermore, thecontact between the sling and a load having a sharp corner is notlimited to a linear zone but is spread over a relatively wide face owingto the compression of the enveloping material of the convex sheath, thecontact area increasing with the load.

In addition, the area of contact between sling and load is not disposedopposite a cable, and this serves to prevent shear in the elastomericmaterial. If loading is such that one cable is located at the outside,it will be initially subjected to a higher force than the interiorcable, but the two cables automatically adjust their positions onaccount of the loop formed by their ends, so that the part of the slingwhich is located beneath the load can reposition itself slightly untilthe forces to which the two cables are subjected balance one another.Finally, the rigidity of the sling is improved because of its convexcross-section, which makes it easier to push a cable beneath a load.

The sheath material may be rubber or polyvinylchloride. It may betransparent so that the cables can be seen and their conditioninspected.

In a preferred method of manufacture, two cables are fed through anextruder in which an enveloping material is extruded around them to forma sheath 2 v tion, the assembly then being cut to provide any desiredlength of sling whereupon the cable ends are bared and interconnected toform a loop.

The invention will now be described with reference to the accompanyingdrawing in which:

FIG. 1 is an elevational view of one exemplary embodiment;

FIG. 2 is a sectional view on the line IIII of FIG. 1;

FIG. 3 is a schematic diagram illustrating a preferred method ofmanufacture;

FIG. 4 is a detail view of a loop formed at one of the ends of the slingshown in FIG. 1;

FIG. 5 is a detail view of a loop in one alternative exemplaryembodiment;

FIG. 6 illustrates another exemplary embodiment;

FIG. 7 illustrates yet another exemplary embodiment;

FIG. 8 is a transverse section on the line VIII-VIII of FIG. 7;

FIG. 9 is a transverse section on the line IX-IX of FIG. 7;

FIG. 10 is a fragmentary view of a sling passing' of another exemplaryembodiment;

FIG. 12 is a view similar to that of FIG. 11, showing yet anotherexemplary embodiment;

FIG. 13 is a transverse sectional view on the line XIIIXIII ofFIG. 12;

FIG. 14 is a fragmentary longitudinal sectional view showing theconstruction of yet another embodiment;

which is relatively flexible and elastic in the cold condi- FIG. 15 isan elevational view of an exemplary embodiment provided withhook-and-eye terminations;

FIG. 16 is a section on the line XVI-XVI of FIG. 15;

FIG. 17 illustrates an alternative method of securing a ring to one endof a sling;

FIG. 18 is a section on the line XVIII-XVIII of FIG. 17;

FIGS. 19 to 23 illustrate various alternative linking strips suitablefor use in constructing slings in accordance with the invention; and

FIGS. 24 to 29 are cross-sectional views of still further embodiments.

In the exemplary embodiment shown in FIGS. 1 and 2, a sling l isconstituted by two metal cables 2a and 2b embedded in a continuoussheath 3 of elastomeric material.

The sheath has an elongate cross-section, and in this embodiment the twofaces 30 and 3b flanking the major axis of the generally ellipticalcross-section are convex. The cables 2a and 2b are preferably made ofstrands twisted in opposite directions in the two cables, in order toavoid any distortion of the sling when it forms a loop or knot. Thecables are located substantially in the longitudinal plane containingthe major axis of the cross-section of the sheath 3, substantiallysymmetrically in relation to the longitudinalaxis of the envelope. Theirends are bared and connect-ed together to form loops l2.

FIG. 3 shows a preferred method of manufacture of the sling l, thecables 2a and 2b being fed from two from the extruder, which cansubsequently be stored until required, and from which the requisitelength for any particular sling can be cut.

In order to form the loops 12 of the sling, the bared ends of the cablescan be looped and joined together, at locations close to the end of thesheath, by two sleeves 9a and 9b, as shown in FIG. 4. Alternatively, anauxiliary cable 18 can be used, which is curved back on itself, its endsbeing clamped by retaining sleeves 9a and 9b to respective extremitiesof the cables 2a and 2b, which in this case have been bared over a shortlength only, as shown in FIG. 5.

Since the load on the sling during use is divided equally between thecables 2a and 2b, but is carried in full by the cable 18, the latterpreferably has a higher strength than that of either of the cables 2aand 2b. However, in certain cases it may be desirable that the weakestpoint of the sling be located in a loop, where it is easy to maintainserveillance, rather than at a point where the cables are embedded inthe solid body of the sheath. In this case, the cable 18 may have thesame strength as each of the cables 2a and 2b, or may even have a lowerstrength than they. The reverse case is equally possible, that is tosay, the cable 18 may be stronger than the two cables 2a and 2bcombined, if it is desired to ensure that any failure should take placebeyond the loop.

If it is desired to fit a sliding attachment to form a running knot, theloop can be engaged in a slip through type of eyelet 10 which containsan elongate opening 11 whose length is grater than the external width ofthe eyelet, as shown in FIG. 6. Preferably the two sleeves 9a and 9b aredisposed inside the arms of the eyelet 10 in order to avoid an excessiverigid length. Alternatively, a half eyelet 10a can be used, as shown inFIG. 5, to engage the auxiliary cable 18 but to limit the length of therigid part.

Since it is frequently desirable to protect the loops, in a simpleembodiment it is possible to form the auxiliary cable 18 from a sectionof sheathed cables similar to or identical with that used to make up thebody of the sling.

Thus, in the embodiment shown in FIGS. 7 to 9, the loop is formed by twoextension cables 18a and 18b located in a sheath 19 which has twomutually opposed convex faces like the body 1 of the sling, albeitpreferably of a smaller section. At each end, the cables 18a and 18b arefixed to the respective cable 2a or 2b by a respective sleeve 9a or 9b.The cables 18a and 18b can have the same strength as the cables 2a and2b, or a lower strength in order to localize possible failures in theloop, or alternatively a higher strength if it is desired to guardagainst failures in the loop. In order to facilitate inspection of theloop, the sheath 19 is preferably made of a transparent material.

The sling just described does not twist, and retains its orientation,even after intensive use. This is due to the fact that when the sling ispassed beneath a load, the cables 2a and 2b are not disposed verticallyin relation to the point of contact but are spaced laterally to a smallextent, on either side of the zone of contact. If the sling containedonly one cable, this would not be the case and the cable could shear theelastomeric material of the sheath. In addition, in the sling described,the upper convex face 3a of the sling flattens under the effect of theload, and this tends to spread the two cables 20 and 2b slightly furtherapart whereas the tension developed in the cables tends to maintain thecables at their initial spacing, an equilibrium being thus establishedbetween these two forces.

When the sling is passed over two sharp edges of a load, the cables donot slide in relation to the sheath and the locations of the sharp edgesof the load, thereby avoiding any risk of the envelope being sheared.Instead, the whole assembly slides over the sharp corners and thesection of the sling which is defined between these sharp corners isurged against the bottom of the load.

In addition, if the sling is passed obliquely beneath a load, as shownin FIG. 10, in such a manner that the rearward cable 2a is initiallysubjected to a larger force than the cable 2b, but the two cables adjustautomatically thanks to the free loops over their ends, and the part ofthe sling located beneath the load deforms slightly until the forces towhich the cables 2a and 2b are subjected are in balance.

The tension in the cables at a point in contact with a sharp angleduring a lifting operation lead to the danger of producing shear in thesheath material. If it is desired to reduce this shear effect, thecables are advantageously bonded to the sheath.

The ratio between the height and the length of the ellipticalcross-section can be selected in accordance with the desiredapplication. This ratio can be small in the case where the load to belifted is not fragile, or may be close to unity if it is necessary toplace around the cables 2a and 2b a substantial quantity of envolopingmaterial, as is the case, for example, if the load to be lifted hassharp angles or is fragile. On the other hand, in a sling having a givenheight and width, cables of different sizes can be used depending uponthe strength which the sling is to have.

In order to reduce the possibility of a sling cable breaking at a sharpcorner of a load, the cables can be provided with deformations in theform of closely spaced beads or fittings. FIG. 11 shows an embodiment ofthe invention in which individual fittings 14 are provided on each cableto form transverse shoulders preventing slippage relative to the sheath.FIGS. 12 and 13 illustrate an embodiment in which fittings 15 areprovided which are common to the cable pair. In these latter Figures,the fitting 15 has two elongate holes 16 through each of which passes acable, 20 or 2b respectively. The ends of the fitting are formed withexternal teeth 17, in order to provide an improved bond between thefittings and the sheath material. The sling is otherwise designed in amanner hereinbefore described, the beads or fittings being slipped overthe cables prior to extrusion.

FIG. 14 illustrates an embodiment in which the cables 2a and 2b are notstraight but deformed to follow a serpentine path within the sheath, theundulations of one cable being symmetrical with respect to those of theother in relation to the longitudinal center-line of the sling. Thesling can thus extend elastically at the same time that the envelopingsheath material located between the cables is compressed or stretched,thereby guarding against failure of the sling when it is subjected to aheavy shock load. The undulations or corrugations can extend over thewhole of the length of the sling or over a part only. The pitch of theundulations in the two cables could also differ from one another, theamplitude of the undulations of larger pitch being smaller than that ofthe undulations of the other, so that the lengths of the serpentineportions of the two cables are substantially the same. The cables arepreferably given the serpentine form prior to extrusion.

FIGS. and 16 illustrate an exemplary embodiment of the invention inwhich one end of the sling 1 has been attached to a ring through themedium of a stirrup link having two legs 21a and 21b which are attachedto the cables 2a and 2b by a common sleeve 22. The other end of thesling 1 has been connected in a similar manner to a hook 23. The legs21a and 21b of the stirrup link are preferably roughened in order toimprove the connection between the link and the sleeve 22.

FIGS. 17 and 18 illustrate an exemplary embodiment in which one of theends of the sling 1 has been secured to a ring 20 by means of a flatanchor plate 24 and a composite link formed by two elements a and 25binterconnected by a pin 26. The plate 24 has a hole 26a (FIG. 19)receiving the element 250 of the composite link, the plate being securedto the cables 2a and 2b by a sleeve 9 which keeps it clamped betweenthese two cables.

The major faces of the plate 24 can be keyed and/or given an undulationin the plane of the plate, as also shown in FIG. 19, and/or currugatedperpendicularly thereto, as shown in FIG. 20.

Instead of being perforated at 26a, the anchor plate 24 may be formedintegrally with a threaded portion 24a as shown in FIG. 21, or a yoke24!) (FIG. 22), or a chain link 24c (FIG. 23). In this latter case, theattachment of the sling to a ring 20 is effected in a manner similar tothat shown in FIG. 17, by slipping a mating element 25b into the ringand attaching that element to the anchor plate by the pin 26.

Alternative sheath cross-sections are shown in FIGS. 24 to 29.

The sling can have one flat face la (FIG. 24),'or even or be of concaveone (not shown), a flattened convex section (FIG. 25). Externalstriations or fluting 27 may be provided to improved its adhesion, asshown in FIG. 26, or a central bead 28 as shown in FIG. 27. Finally, oneor more internal cavities 29 or 30 may be provided, as shown in FIGS. 28and 29 respectively.

The cables 20 and 2b can be made of a natural or synthetic textilematerial instead of metal. As will be noted particularly from FIGS. 2and 24-29, the axes of cables 2a, 2b substantially coincide with thecenters of curvature of the generally elliptical cross-section of thesheath 3 at opposite ends of its major axis.

The individual features described can be combined in various ways, andmodified to form further embodiments of the invention.

What we claim as our invention and desire to secure by Letters Patent ofthe United States is:

l. A sling comprising two spaeedly juxtaposed cables embedded in acontinuous elastomeric sheath and provided with interconnectedextremities projecting from said sheath and forming a pair of loops atopposite ends thereof, said sheath having a generally ellipticalcrosssection with the major axis of the ellipse substantially passinthrough the axes of said cables on opposite sides 0 the longitudinalcenterline of the sheath and at substantially equal distances from saidcenterline, the axes of said cables substantially coinciding with thecenters of curvature of said cross-section at opposite ends of saidmajor axis.

2. A sling as defined in claim 11 wherein said cables are provided withdeformations within said sheath for preventing relative longitudinalslippage between said sheath and said cables.

3. A sling as defined in claim 2 wherein said deformations areundulations of said cables. i

4. A sling as defined in claim 3 wherein said undulations are mutuallysymmetrical.

5. A sling as defined in claim 2 wherein said deformations arelongitudinally spaced fittings on said cables.

6. A. sling as defined in claim 5 wherein said fittings are part of aset of transverse links interconnecting said cables within said sheath.

1. A sling comprising two spacedly juxtaposed cables embedded in acontinuous elastomeric sheath and provided with interconnectedextremities projecting from said sheath and forming a pair of loops atopposite ends thereof, said sheath having a generally ellipticalcross-section with the major axis of the ellipse substantially passingthrough the axes of said cables on opposite sides of the longitudinalcenterline of the sheath and at substantially equal distances from saidcenterline, the axes of said cables substantially coinciding with thecenters of curvature of said cross-section at opposite ends of saidmajor axis.
 1. A sling comprising two spacedly juxtaposed cablesembedded in a continuous elastomeric sheath and provided withinterconnected extremities projecting from said sheath and forming apair of loops at opposite ends thereof, said sheath having a generallyelliptical cross-section with the major axis of the ellipsesubstantially passing through the axes of said cables on opposite sidesof the longitudinal centerline of the sheath and at substantially equaldistances from said centerline, the axes of said cables substantiallycoinciding with the centers of curvature of said cross-section atopposite ends of said major axis.
 2. A sling as defined in claim 1wherein said cables are provided with deformations within said sheathfor preventing relative longitudinal slippage between said sheath andsaid cables.
 3. A sling as defined in claim 2 wherein said deformationsare undulations of said cables.
 4. A sling as defined in claim 3 whereinsaid undulations are mutually symmetrical.
 5. A sling as defined inclaim 2 wherein said deformations are longitudinally spaced fittings onsaid cables.